Why did Jesus die?1 Our question is not about the manner of his death (in what way?), the means of his death (how?), nor its circumstances (when?)2; It is about the reason and intended results of his death. Although we cannot exhaustively answer this question, we can nevertheless answer it truly.3 In order to do this briefly, we will consider just one of the ancient eyewitness sources written about Jesus’ life and death—namely, the Gospel of John.4
There are several places in John where Jesus says that he “came” or “does [x, y, or z]” for a reason or purpose.5 Some of these relate most closely with the ultimate purpose for which Jesus died (14:31; 18:37), while others address the results or entailments of that purpose. In this post, we will first consider Jesus’ ultimate purpose in dying and then the results entailed in his accomplishment of that purpose.
In John 14, Jesus prepares his disciples for the time when he departs (i.e., in death), and he says, “I do as the Father has commanded me, so that the world may know that I love the Father” (14:31, ESV).6 Here Jesus describes his voluntary death as obedience to the Father, and that obedience is purposed to display the love of God the Son for God the Father.7 In John 18, Pilate interrogates Jesus, and Pilate storms out after Jesus says the following: “For this purpose I was born and for this purpose I have come into the world—to bear witness to the truth. Everyone who is of the truth listens to my voice” (18:37).8 In light of Jesus’ repeated testimony about himself (e.g., 8:12–14) and his singular statement of John 14:6 that “I am the way, the truth, and the life,” we ought to conclude with D. A. Carson that “in this context, truth . . . is nothing less than the self-disclosure of God in his Son.”9 Therefore, Jesus came to die as the unique God (1:18)—God’s unique Son (3:16)—in order to uniquely reveal the glorious character of the triune God (1:14–17). This may strike you as unexpected! Yet, what Jesus reveals and his purpose to reveal are inseparable10, so we turn to Jesus’ intended results.
If the death of Jesus intends to uniquely reveal God’s glorious character, then what precisely does the death of God the Son make known? In short, Jesus’ death reveals God as the Lamblike Servant whose humble substitution and sacrifice on the cross is the only way for sinners to have eternal life.
John narrates that truth in the following ways: After taking on flesh (1:14), God himself as Jesus is identified as the Lamb (1:29 cf. Isa 53:7), who takes away the sin of fallen humanity.11 Apart from this divine intervention, humanity would only love the darkness (3:19–21) with the wrath of righteous judgment awaiting them (3:36).12 Jesus indicates that believing and knowing that “I Am He” is the only way not to die in your sins (8:24–28 cf. Isa 43:10–11).13 With that deplorable and desperate condition of his sheep in view, God the Son is revealed as the Good Shepherd who lays down his life for the sheep (John 10:15–18), dying in their place. Substituting himself for them, Jesus dies bearing the judgment for their sins about the time the Passover lamb was slain (19:14), without a broken bone (19:33, 36 cf. Exod 12:46), and his body was not left to the morning (John 19:31 cf. Exod 12:10).14
Therefore, Jesus’ death, by saving sinners as a substitutionary sacrifice and providing them with eternal life, accomplishes its ultimate purpose of uniquely revealing God Himself for “this is eternal life, that they know You, the only true God, and Jesus Christ whom you have sent” (John 17:3).
 Given the brevity of this post and the importance of the topic, I also recommend John Piper, Fifty Reasons Why Jesus Came to Die (Wheaton, IL: Crossway Books, 2006).
 It is also not about whether he must die; for the eyewitness accounts of the Gospels are replete with the times Jesus said he must. See, for example, Matt 16:21; Mark 8:31; Luke 9:22, 17:25, 22:37, 24:7, 26; John 3:14 cf. 12:32–34.
 I am alluding to D. A. Carson’s adage against post-modern thinking: “Although we cannot know anything absolutely (i.e., exhaustively) like God knows it, we can know some things truly (i.e., really).” Andrew David Naselli, “D. A. Carson’s Theological Method,” SETS 29.2 (2011): 252.
 On the Gospels as eyewitness testimony, see Richard Bauckham, Jesus and the Eyewitnesses: The Gospels as Eyewitness Testimony, 2nd ed. (Grand Rapids: Eerdmans, 2017); on the trustworthiness of the Gospels as ancient accounts, see Peter J. Williams, Can We Trust the Gospels? (Wheaton, IL: Crossway, 2018).
 So, for example, John 3:16, 17 cf. 12:46, 47; 5:34; 6:38; 9:39; 10:10; 14:13, 31 cf. 17:4; 18:37.
 In Greek, the purpose clause is placed first for emphasis: “in order that the world would know that I love the Father, just as the Father commanded me, thus I do.”
 On the voluntary nature of Jesus’ death, one should recall John 10:18; Jesus says, “No one takes [my life] from me, but I lay it down of my own accord. I have authority to lay it down, and I have authority to take it up.” That John believes Jesus voluntarily died is clear from his description of Jesus’ death in 19:30, where Jesus “bowed his head and handed over his spirit.” The description recalls the authority of Jesus to lay down or hand over his own life.
 We should hear John 10:16, 27 in that reply. There Jesus says that his sheep listen to his voice. Therefore, all sheep are those who are “of the truth”—vitally connected to him who is the truth, Jesus. Seen in this light, Being a sheep and being of the truth are parallel to being a branch in the True Vine (John 15:1–11).
 D. A. Carson, The Gospel According to John, The Pillar New Testament Commentary (Downers Grove, IL: InterVarsity Press, 1991), 595.
 This is to say that if Jesus desires to display the character of God, then that desire has an object or content that is meant for display also. That object or content is inseparably included within the ultimate purpose of his death.
 John later describes this as the giving of God the Son so that all who believe would have eternal life and thus be saved (3:16–17).
 This is due to spiritual blindness (9:39–41).
 Thus, “no one comes to the Father except through me” (14:6).
 These three details along with John 1:29 confirm that John views Jesus’ death as that of the Passover Lamb of the new exodus. For more on the Passover and Servant connections, see Paul M. Hoskins, That Scripture Might Be Fulfilled: Typology and the Death of Christ (Longwood, FL: Xulon Press, 2009).